Caerleon is a site of considerable archaeological importance as the location of a Roman legionary fortress or castra. It was the headquarters for Legio II Augusta from about 75 to 300 AD, and on the hill above was the site of an Iron Agehillfort.[3]
The Romans called the site Isca after the River Usk (Welsh Wysg). The name Caerleon may derive from the Welsh for "fortress of the legion"; around 800 AD it was referred to as Cair Legeion guar Uisc.[4]

Substantial excavated Roman remains can be seen, including the military amphitheatre, thermae (baths) and barracks occupied by the Roman Legion. In August 2011 the remains of a Roman harbour were discovered in Caerleon.[5] According to Gildas, followed by Bede, Roman Caerleon was the site of two early Christianmartyrdoms, those of Julius and Aaron. Recent finds suggest Roman occupation of some kind as late as AD 380.[6] Roman remains have also been discovered at The Mynde, itself a distinctive historical site.[7]

During the Middle Ages, Caerleon or nearby Venta Silurum (now Caerwent) was the administrative centre of the Kingdom of Gwent. The parish church, St Cadoc's was founded on the site of the legionary headquarters building probably sometime in the 6th century. A Norman-style motte and baileycastle was built outside the eastern corner of the old Roman fort, probably by the Welsh Lord of Caerleon, Caradog ap Gruffydd. It was held in 1086 by Turstin FitzRolf, standard bearer to William the Conqueror at Hastings. From the apparent banishment of Turstin by William II, it was held from 1088 by Wynebald de Ballon, brother of Hamelin de Ballon who held Abergavenny further up the River Usk. Battles raged between the Welsh and Normans and in 1171 Iorwerth ab Owain and his two sons destroyed the town of Caerleon and burned the Castle. Caerleon was an important market and port and presumably became a borough by 1171, although no independent charters exist. Both castle and borough were seized by William Marshal in 1217 and Caerleon castle was rebuilt in stone. The remains of many of the old Roman buildings stood to some height until this time and were probably demolished for their building materials.

During the Welsh Revolt in 1402 Rhys Gethin, General for Owain Glyndŵr, took Caerleon Castle together with those of Newport, Cardiff, Llandaff, Abergavenny, Caerphilly and Usk by force.[8] This was probably the last time Caerleon castle was ruined, though the walls were still standing in 1537 and the castle ruins only finally collapsed in 1739 - their most obvious remnant is the Round Tower at the Hanbury Arms public house. The Tower is a Grade II* listed building.[9]

The old wooden Caerleon Bridge was destroyed in a storm in 1779 and the present stone version was erected in the early 19th century. Until the Victorian development of the downstream docks at Newport Docks, Caerleon acted as the major port on the River Usk. The wharf was located on the right bank, to the west of today's river bridge which marked the limit of navigability for masted ships. A tinplate works and mills were established on the outskirts of the town, in Ponthir, around this time, and Caerleon expanded to become almost joined to Newport.[10]

A plaque on the Mynde wall in High Street references the Newport Rising of 1839 in which John Frost of Newport was a prominent figure in the Chartist movement. John Jenkins, owner of Mynde House and owner of Ponthir Tinplate Works, built the wall to keep demonstrators out.

The name of the former Drovers' Arms on Goldcroft Common bore witness to the ancient drovers' road on the old road from Malpas. It is thought that the common itself was once the site of a cattle market.[11]

Writing in 1951, local historian and folklorist Fred Hando described the traditional journey through Caerleon of the Mari Lwyd or "Venerable Mary", a tradition similar to that of Hoodening found in Kent, Padstow and Cheshire, and involving a man dressed with a horse's skull. The jaw of the skull could be made to move, with the aid of rods. Hando's informant, Gus Sergeant of Bulmoor, reported that the Mari Lwyd had not been seen in the town for at least 20 years, but he was still able to describe it:

"We filled the eye-holes with wadding and 'pop alleys' and fixed great ears made of wadding stiffened with cardboard; then we stuck rosettes on the sides of the skull and strung long coloured ribbons as reins."

One man acted as leader of the Mari, holding the ribbons, and then came the Mari itself draped in a white sheet. It was followed by three singers, who sang in Welsh although "they didn't understand the words". On occasion, the procession of the Mari Lwyd would start as far north as Newbridge-on-Usk and proceed through the town, ending as far south as Goldcliff. The party would be invited into houses along the way and given "money and home-made cakes and gallons of beer". Another of Hando's informants provides a description, dated 1841, of the Yuletide tradition:

"The custom of chaunting at their neighbours' doors on the twelfth night ... on which occasion they are fantastically dressed with ribbons of various colours. One of the party carries a horse's head decorated in the same manner. Representations of trees, to which are appended apples and oranges, are also carried about, and on one of the branches an artificial bird, called "Aderyn Pica Llwyd" (the grey hobgoblin bird) is placed."[12]

Geoffrey makes Arthur's capital Caerleon and even Sir Thomas Malory has Arthur re-crowned there. The still-visible Roman amphitheatre at Caerleon has been associated with Arthur's 'Round-Table' element of the tales;[14] and has been suggested as a possible source for the legend.[15]

"For it was located in a delightful spot in Glamorgan, on the River Usk, not far from the Severn Sea. Abounding in wealth more than other cities, it was suited for such a ceremony. For the noble river I have named flows along it on one side, upon which the kings and princes who would be coming from overseas could be carried by ship. But on the other side, protected by meadow and woods, it was remarkable for royal palaces, so that it imitated Rome in the golden roofs of its buildings... Famous for so many pleasant features, Caerleon was made ready for the announced feast." (Historia Regum Britanniae "History of the Kings of Britain")

Caerleon also has associations with later Arthurian literature as the birthplace of the writer Arthur Machen who often used it as a location in his work. The Hanbury Arms was visited by Tennyson who lodged there while he wrote his Morte d'Arthur (later incorporated into his Idylls of the King).[17] Today Caerleon has a modern statue of a knight, "The Hanbury Knight", in reflecting stainless steel by Belgian sculptor Thierry Lauwers.[18] In Michael Morpurgo's novel Arthur, High King of Britain, Caerleon is the castle where Arthur unknowingly commits incest with his half-sister Morgaine, resulting in the conception of his son Mordred who will later bring about his downfall. Mary Stewart's account of the Arthurian legends also mentions Caerleon as a place where Arthur held court. In that telling, the incest took place at Luguvalium.[19]

Caerleon is centred around a small common. Goldcroft Common is the only remaining of the seven commons of Caerleon. Most of the small businesses of Caerleon are near the common as is the Town Hall which has a World War I and World War II memorial garden. Caerleon library is located within the Town Hall and is associated with Newport Central Library. The intersection of High Street and Cross Street is known as The Square.

The municipal playing fields are at Caerleon Broadway and a children's playground is in Cold Bath Road. Private sport and leisure facilities are available at the Celtic Manor. Caerleon has a few restaurants, cafés and take-away food outlets and many public houses that have restaurant facilities. The Ffwrrwm is a small specialist shopping courtyard with an eclectic display of sculpture. Caerleon also has its own station of Gwent Police and an active community policing presence.

The centre of Caerleon sits in the Vale of Usk and the River Usk forms part of the community's southern boundary. In the north-west part of the town, across the railway bridges, the land rises sharply up to Lodge Wood and its hill fort. The community's western boundary is formed by the A4042 road (Heidenheim Drive) and the northern boundary partly by the Malthouse Road and partly by the Afon Llwyd river which flows southwards to the River Usk along the town's eastern side. Across the River Usk from Caerleon, to the south-east and east, St Julian's Park, the village of Christchurch and the upland region around Christchurch Hill as far as the M4 motorway and the A449 road are also within the community.

Conversely, traffic joining the M4 from Caerleon can join the M4 eastbound at Junction 25 but to join the M4 westbound traffic must follow the Junction 25A offslip, Heidenheim Drive, Malpas Road route to M4 Junction 26. Alternatively, traffic can join the M4 both eastbound and westbound at Junction 24.

The centre of Caerleon (High Street, Mill Street and Castle Street) is a one-way traffic system and there are car parks at Broadway and Cold Bath Road. A regular bus service links Caerleon to Newport city centre and Cwmbran. There is a limited City Sightseeing open-top bus service in summer months. A cycle and pedestrian walkway alongside the River Usk links Caerleon to Malpas and Newport city centre at Crindau, route 88 of the National Cycle Network.[20]

Education is generally conducted in the English language in schools but at least a mandatory Welsh language content must be provided under the Welsh education curriculum. There are no Welsh-medium education schools in Caerleon but there are three primary schools elsewhere in Newport; Ysgol Gymraeg Bro Teyrnon in Brynglas, Ysgol Gymraeg Casnewydd in Ringland and Ysgol Gymraeg Ifor Hael in Bettws. The nearest Welsh-medium secondary school is Ysgol Gyfun Gwynllyw in Trevethin, Pontypool.

A former campus of the University of South Wales is located in Caerleon. The campus closed on 31 July 2016. The campus was the main campus of the University of Wales, Newport and the second largest campus of the University of South Wales after the merger of universities in 2013. It hosted a variety of undergraduate and postgraduate courses, including education, sports and photography. The campus had extensive sports facilities, library, students' union shop, students' union bar and accommodation blocks.

During September 2014, It was announced by the University of South Wales that the Caerleon campus would close in 2016[23] with courses being integrated into the remaining campuses. The University intends to sell the campus for housing development but there is strong opposition to the proposed re-development from local residents.[24] The Caerleon Civic Society has asked Cadw, the body that looks after historic monuments and buildings in Wales, to give the Edwardian main building Grade II Listed building status to save it from demolition.[25]
On 7 August 2016 the Welsh Government announced that they would recommend that the main building, gatehouses and gate-piers be listed as ‘buildings of special architectural and historic interest’. The University of South Wales expressed their continued opposition to the proposed listing but the announcement was welcomed by local politicians and the Caerleon Civic Society.[26] Grade II listing of the Main Building, the Principal’s Residence, Gate Piers and Caretaker’s / Gardener’s Lodge was confirmed on the 3 March 2017
.[27]

Historically housing was largely located on the west bank of the River Usk between Caerleon Bridge and Caerleon Common with a small number of houses on the east bank. A number of substantial housing developments have been created to the West of Caerleon: Lodge Hill, Home Farm, Roman Reach, Trinity View, Brooklea and The Brades as well as smaller cluster developments near the centre of the town. Substantial housing developments in nearby Ponthir and Cwmbran has also increased traffic congestion in Caerleon.

In July 1934 land at Bulmore Farm was acquired to build an open-air swimming pool, cafe and restaurant. Bulmore Lido, as it became well known, opened to members of the public in July that year.[28] It closed in the 1980s.

The Caerleon ward is home to the Celtic Manor Resort, location of the 2010 Ryder Cup.[29] Caerleon also has a good quality 9-hole municipal golf course, driving range and golf clubhouse. However, during winter months the golf course is prone to flooding due to its location alongside the River Usk.

Live music events and Visual arts are staged at venues including the open-air Roman Amphitheatre, which hosts plays in the summer.

An informative and wide-ranging history of Caerleon was published in 1970 by local amateur historian Primrose Hockey MBE,[31] who was a founder member of Caerleon Local History Society. An archive of her local history collection is kept by the Gwent Record Office.[32]